linux-kernel - Re: [PATCH v7 05/14] arm64/numa: avoid inconsistent information to be printed

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Date:   Wed, 31 Aug 2016 10:29:16 +0800
From:   "Leizhen (ThunderTown)" <thunder.leizhen@...wei.com>
To:     Will Deacon <will.deacon@....com>
CC:     Catalin Marinas <catalin.marinas@....com>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Rob Herring <robh+dt@...nel.org>,
        "Frank Rowand" <frowand.list@...il.com>,
        devicetree <devicetree@...r.kernel.org>,
        Zefan Li <lizefan@...wei.com>, Xinwei Hu <huxinwei@...wei.com>,
        Tianhong Ding <dingtianhong@...wei.com>,
        Hanjun Guo <guohanjun@...wei.com>
Subject: Re: [PATCH v7 05/14] arm64/numa: avoid inconsistent information to be
 printed



On 2016/8/31 1:51, Will Deacon wrote:
> On Sat, Aug 27, 2016 at 04:54:56PM +0800, Leizhen (ThunderTown) wrote:
>>
>>
>> On 2016/8/26 20:47, Will Deacon wrote:
>>> On Wed, Aug 24, 2016 at 03:44:44PM +0800, Zhen Lei wrote:
>>>> numa_init(of_numa_init) may returned error because of numa configuration
>>>> error. So "No NUMA configuration found" is inaccurate. In fact, specific
>>>> configuration error information should be immediately printed by the
>>>> testing branch.
>>>>
>>>> Signed-off-by: Zhen Lei <thunder.leizhen@...wei.com>
>>>> ---
>>>>  arch/arm64/mm/numa.c | 6 +++---
>>>>  1 file changed, 3 insertions(+), 3 deletions(-)
>>>>
>>>> diff --git a/arch/arm64/mm/numa.c b/arch/arm64/mm/numa.c
>>>> index 5bb15ea..d97c6e2 100644
>>>> --- a/arch/arm64/mm/numa.c
>>>> +++ b/arch/arm64/mm/numa.c
>>>> @@ -335,8 +335,10 @@ static int __init numa_init(int (*init_func)(void))
>>>>  	if (ret < 0)
>>>>  		return ret;
>>>>
>>>> -	if (nodes_empty(numa_nodes_parsed))
>>>> +	if (nodes_empty(numa_nodes_parsed)) {
>>>> +		pr_info("No NUMA configuration found\n");
>>>>  		return -EINVAL;
>>>
>>> Hmm, but dummy_numa_init calls node_set(nid, numa_nodes_parsed) for a
>>> completely artificial setup, created by adding all memblocks to node 0,
>>> so this new message will be suppressed even though things really did go
>>> wrong.
>> It will be printed by the former: numa_init(of_numa_init)
> 
> Does that print an error for every possible failure case? What about the
> acpi path?
I think acpi path should print error by itself. The reason maybe:
1. In numa_init and its sub function, all error paths printed error immediately, except arm64_acpi_numa_init.
2. Suppose numa_init returns error, we do not print the returned error code, so the user don't known what problem cause acpi numa failed.


> 
>>> In that case, don't we want to print *something* (like we do today in
>>> dummy_numa_init) but maybe not "No NUMA configuration found"? What
>>> exactly do you find inaccurate about the current message?
>> For example:
>> [    0.000000] NUMA: No distance-matrix property in distance-map
>> [    0.000000] No NUMA configuration found
>>
>> So if of_numa_init or arm64_acpi_numa_init returned error, because of
>> some numa configuration error had been found, it's no good to print "No
>> NUMA ...".
> 
> Sure, I'm all for changing the message. I just think removing it is
> probably unhelpful. Something like:
> 
> "NUMA: Failed to initialise from firmware"
I think adding this into arm64_acpi_numa_init will be better, maybe we should print 'ret' further:

int __init arm64_acpi_numa_init(void)
{
	int ret;

	ret = acpi_numa_init();
	if (ret) {
+		pr_info("Failed to initialise from firmware\n");
		return ret;
	}

> 
> might do the trick?
> 
> Will
> 
> .
>